I can speak only for myself, but the objection to the withdrawal from Syria was 1)
It seemed Ill conceived and hastily arrived at; 2) did not appear to enhance any strategic interest of the US; 3) left the Kurds (up to then our main fighting ally in Syria) high and dry; but most importantly 4) was a huge kow-tow to Erdogan, who is definitely not our ally, so he could a) invade the part of Syria that would be Kurdistan, once again betraying the Kurds. In other words, I objected because it seemed a pointless action that benefited only Turkey. And since the military establishment did not support it, the only real effect was that our troops moved to another area nearby.

I have no problem withdrawing from Afghanistan, where we have no business being anyway, before it destroys us like it did the UK and the Soviet Union.